Danny Welbeck has scored eight goals since his summer arrival to Arsenal.(Reuters)

Arsenal striker Danny Welbeck has claimed he "tried to be respectful" with Manchester United after scoring the winner on his return to Old Trafford during the FA Cup quarter final on 9 March, 2015.

Welbeck left Old Trafford on deadline day this summer to move to the Emirates Stadium for a reported fee of £16m ($24m) after United manager Louis van Gaal claimed he was not good enough for Old Trafford.

"Danny Welbeck was here from when he was nine. He has played, after [his 2010-11 loan at] Sunderland, three seasons at Manchester United but he doesn't have the record of [Robin] Van Persie or [Wayne] Rooney and that is the standard. That is why we let him go – because of Falcao but also the youngsters who can fit in," van Gaal then justified.

And while Falcao spent another game on the bench Welbeck took advantage of Antonio Valencia's mistake in the second half to give the Gunners a 2-1 victory over his childhood side and book their place in the FA Cup semi-finals – where they will face Bradford or Reading.

"It was a great reception. It was hard for me but I tried to be respectful," the striker said. "It was about being professional, keeping my focus and motivation. I kept plugging away and then got on the end of Antonio Valencia's backpass, beat David de Gea and got the winning goal. I'm just really pleased we're through to the next round."

The former Old Trafford academy star says he tried to be professional despite facing his former side, while expressing his happiness over helping Arsenal to reach the semifinal.

"I stayed professional and I was just doing my job. To be able to get back on the scoresheet and get through to the next round is the most important thing. It's good for the team that we're through to the next round, in the semi-finals at Wembley. To get the goal was good for me but it was all about the team performance tonight."